RENO, Nev. — On the eve of a trip abroad intended to burnish his qualifications to be commander in chief, Mitt Romney accused Obama administration officials on Tuesday of betraying the country by leaking national security secrets for their own political gain and failing to stand up to adversaries like China, Russia and Iran.
Mr. Romney’s address, at the Veterans of Foreign Wars convention here, was the most expansive foreign policy speech of his candidacy and opened a new and aggressive attack on President Obama on national security.
The Republican challenger has struggled to gain traction on foreign policy issues against Mr. Obama, who has enjoyed public support for the raid that killed Osama bin Laden and good marks in polls for his handling of American diplomacy.
“This conduct is contemptible,” Mr. Romney said of leaks for which he blames the administration. “It betrays our national interest. It compromises our men and women in the field. And it demands a full and prompt investigation by a special counsel, with explanation and consequence.”
The speech highlighted a broader theme that Republicans have been pressing: that Mr. Obama and his administration “betrayed” the trust of America’s closest allies — Mr. Romney used a form of that word three times in the speech — forsaking nations like Poland, the Czech Republic and particularly Israel, whose leaders the president “is fond of lecturing,” Mr. Romney said.
“He has undermined their position, which was tough enough as it was,” Mr. Romney said. “And even at the United Nations, to the enthusiastic applause of Israel’s enemies, he spoke as if our closest ally in the Middle East was the problem.”
While Mr. Romney’s speech was notable for the intensity of his attacks against Mr. Obama, it was also notable for a lack of new policy specifics. That seemed to underscore how much his campaign has struggled to find sharp contrasts with the White House on foreign policy, outside of a few clear differences, like Mr. Romney’s call to reject a new strategic missile treaty with Russia and his opposition to engaging the Taliban in peace talks in Afghanistan. Some experts also say that Mr. Obama has been a strong supporter of Israel and that Mr. Romney has offered little tangible policy to illustrate how he would significantly improve on that.
The focus on Israel comes as Mr. Romney begins an overseas trip on Wednesday that is to take him to Britain, Poland and Israel. His meetings with Israeli leaders are expected to provide a sounding board for his concerns about the Iranian nuclear threat and what he considers the Obama administration’s lack of resolve in confronting it.
Mr. Romney’s provocative choice of words added to Republican efforts to define Mr. Obama as out of step with basic American goals and values at home and abroad. High-profile Republicans have been attacking Mr. Obama as hostile to free enterprise and intent on a greater government role in the economy. In his speech Tuesday, Mr. Romney cast himself as an “unapologetic believer in the greatness” of the United States while characterizing Mr. Obama as a leader who has “given trust where it is not earned, insult where it is not deserved, and apology where it is not due.”
His critique of Mr. Obama’s record in the Middle East came against the backdrop of especially intense criticism of the administration from the right. Neoconservatives have assailed the White House for not taking a harder line against Iran. Evangelical Christians are demanding more robust American support for Israel. And a group of Congressional Republicans including Representative Michele Bachmann of Minnesota has claimed without any evidence that a top State Department aide has ties to the Muslim Brotherhood, an assertion that other Republicans, including Senator John McCain of Arizona, have excoriated as ludicrously false.
Criticizing Mr. Obama for not doing more to support Iranian democracy demonstrations, Mr. Romney said dissidents in Tehran “should hear the unequivocal voice of an American president affirming their right to be free.” The people of Israel, Mr. Romney said, “deserve better than what they have received from the leader of the free world.” (Some Israeli leaders do not share this view; Ehud Barak, the defense minister and former prime minister, said last year that Mr. Obama had been an “extremely strong supporter of Israel in regard to its security.” They also have praised Mr. Obama for opposing the Palestinian Authority’s bid for statehood at the United Nations.)
The Obama camp continued to pound Mr. Romney’s coming foreign trip, calling it short on substance and light on stops.
Jay Carney, the White House spokesman, declined to comment on Mr. Romney’s criticism of an investigation into leaks but said Mr. Obama “has made abundantly clear that he has no tolerance for leaks.” And Vice President Joseph R. Biden Jr. assailed Mr. Romney’s speech as “empty rhetoric and bluster.” Mr. Biden said, “He reflexively criticizes the president’s policies without offering any alternatives.”
In his speech, Mr. Romney for the first time demanded that Iran halt all nuclear enrichment activities, but he did not say what he would do as president if the Iranians failed to accede to his demand. Both Mr. Romney and Mr. Obama have said that military action is an option should the Iranians pursue construction of a nuclear device. The Romney campaign also said Tuesday that it would make $1.3 billion in military aid to Egypt conditional on that country’s maintaining a peace agreement with Israel.
Republicans appear to be hoping the controversy over leaks will snowball into a major political issue before the election.
Two federal prosecutors appointed by Attorney General Eric H. Holder Jr. are investigating the disclosure of details of cyberattacks against Iran’s nuclear program as well as leaks about the foiling of a plot by Al Qaeda in Yemen to bring down an airliner with an underwear bomb. Republicans have also objected to leaks about the direct role Mr. Obama plays in ordering assassinations through drone strikes.
In making such a stark accusation about White House complicity in leaks, Mr. Romney and his aides pointed to Senator Dianne Feinstein, a Democrat from California and chairwoman of the Senate Intelligence Committee, who on Monday was quoted as saying that “some” national security leaks had to be coming from the White House but that Mr. Obama was not behind them.
Immediately after Mr. Romney’s speech here, Ms. Feinstein backed away from her comments and said she was “disappointed” in how Mr. Romney had characterized her statement. “I stated that I did not believe the president leaked classified information,” she said. “I shouldn’t have speculated beyond that, because the fact of the matter is I don’t know the source of the leaks.”
During the speech, Mr. Romney vowed that while he was overseas he would keep with tradition and not criticize the incumbent’s foreign policy — though that did not stop him in Reno from attacking Mr. Obama before he stepped on the plane.
“I will tell you right here — before I leave — what I think of this administration’s shabby treatment of one of our finest friends,” Mr. Romney said, describing what he said was Mr. Obama’s weak support for Israel.
And while Mr. Romney has taken criticism for refusing to commit explicitly to a drawdown of nearly all American troops from Afghanistan by 2014 — the timeline backed by Mr. Obama and NATO leaders — he reiterated his “goal” to have combat troops out that year but suggested the timing would still depend on feedback from military commanders about conditions on the ground.