For President Obama, the combination of negotiations, new sanctions aimed at Iran’s oil revenues and increased military pressure is the latest — and perhaps the most vital — test of what the White House calls a “two track” policy against Iran. In the midst of a presidential election campaign in which his opponent, Mitt Romney, has accused him of being “weak” in dealing with the Iranian nuclear issue, Mr. Obama seeks to project toughness without tipping into a crisis in the region.

At the same time he must signal support for Israel, but not so much support that the Israelis see the buildup as an opportunity to strike the Iranian nuclear facilities, which Mr. Obama’s team believes could set off a war without significantly setting back the Iranian program.

A key motivation for “Olympic Games,” the covert effort to undermine Iran’s enrichment capability with cyberattacks, has been to demonstrate to the Israelis that there are more effective ways to slow the program than to strike from the air.

But this delicate signaling to both Iran and Israel is a complex dance. Senator John Kerry, the Massachusetts Democrat who is chairman of the Foreign Relations Committee, said that the administration must strike a fine balance between positioning enough forces to deter Iran, but not inadvertently indicate to Iran or Israel that an attack on Iran’s nuclear sites is imminent or inevitable.

“There are a lot of expectations to manage,” Mr. Kerry said in an interview. “People need to know you’re serious, but you must also leave room for peaceful resolution. It’s very important not to take steps that send the wrong messages here.”

There is little evidence that the increased pressure is having the desired effect. Negotiations with Iran are at a stalemate, though a group of Iranian, American and European experts are expected to meet in Istanbul on Tuesday to review a recent American proposal and Iranian response. So far, though, Iran has strenuously resisted all efforts to force it to give up enrichment of uranium, starting with production of a type that is considered relatively close to bomb grade.