WASHINGTON (Reuters) - Washingtons push on Pakistan to get tough on suspected militants on its territory is prompted by worries about an attack on US soil, a concern the United States will press in talks with Islamabad later this month. A US official last week countered suggestions that the tougher approach is driven by the need to show progress ahead of the October 22 talks by an Obama administration strategy review of the war in Afghanistan in December. The failed Times Square bombing in May and the recent terrorism alert for Europe fuelled fears of an attack, prompting the stepped up drone attacks in Pakistans rugged northwest and pointed US comments pressing Islamabads to pursue militants more aggressively. There is really mounting concern that we are extremely vulnerable to an attack from a group in Pakistan that could occur, the US official said, speaking on condition of anonymity. Such an attack would trigger a critical change in ties with Islamabad, the official warned. (An attack) will change the nature of the relationship, not because necessarily it makes sense to, but because the congressional outcry and the public outcry will be such that you will have to dramatically do things quite differently, the official added. The Obama Administration official agreed that ratcheting up pressure on Pakistan ... is not the way to get them to do things. With Pakistan, as with most countries, the more public and vocal you are, the harder things get, he said. But the US will continue to deliver the message that Pakistan needs to do more against insurgent groups, even at the strategic review. It doesnt need to be confrontational, the official said. We will continue with this message, he said. We have constant communications with the Pakistanis. They know where were at. A congressionally mandated White House report sent to Capitol Hill this week assessing the war strategy said Pakistan had failed to move aggressively against Al-Qaeda and the Afghan Taliban last spring, in part for political reasons. The Obama Administration official denied any Machiavellian plan to put pressure on Islamabad to move more aggressively ahead of the US-Pakistan Strategic Dialogue or Obamas December strategy review. The report was due when it was due, the official said, calling it a candid assessment to help Congress understand the challenges. The remarks highlighted in news accounts were more negative than the overall report, including classified sections that remain secret, he said. We were trying to tell Congress that the situation in Pakistan is rather dire and that were concerned, the official said. Were worried that the day after tomorrow, there could be an attack that originates from Pakistan, from one of these groups, and that things will change dramatically.