Washington ( CNN ) -- The United States is watching closely to the see the ultimate fate of the most powerful man in Pakistan , Gen. Ashfaq Parvez Kayani , the Pakistani army 's chief of staff . Pressured by Washington to crack down on terrorists at the same time he was kept in the dark about the U.S. raid to kill Osama bin Laden , Kayani `` is facing more vocal and strident criticism than he has in the past , '' a senior U.S. military official told CNN . `` We really think he is coming under increased scrutiny by junior and mid-grade officers . '' This is the type of scrutiny senior Pakistani generals like Kayani are `` not accustomed to facing , '' the official said . Criticism of Kayani inside Pakistan had grown in recent months as he became close to the Obama administration and the Pentagon . But in the wake of the U.S. military raid into Pakistan to kill bin Laden , the criticism has increased from an officer corps furious that U.S. troops invaded Pakistan 's territory without the Pakistani military , and especially Kayani , being consulted . Adm. Michael Mullen , chairman of the U.S. Joint Chiefs of Staff , is one of Kayani 's closest professional and personal allies , having met with him many times in the past several years . `` Mullen does consider him a friend , '' said the admiral 's spokesman , Capt John Kirby . `` That does n't mean there are n't still disagreements . It does n't mean Kayani does n't feel betrayed . '' U.S. officials are closely watching a group known as the `` 11 corps commanders , '' the senior Pakistani generals hand-picked by Kayani to command . Keeping their loyalty will be crucial for Kayani to keep his job . At his final Pentagon news conference Thursday before stepping down at the end of the month , Gates warned that no matter how much strain exists between the two countries , cooperation must be preserved . `` We need each other and we need each other more than just in the context of Afghanistan . Pakistan is an important player in terms of regional stability and in terms of central Asia , and my view is that this is a relationship that we need to keep working at it . '' Incoming Defense Secretary Leon Panetta on June 9 sounded a similar warning : `` This is a difficult challenge . The relationship with Pakistan is at the same time one of the most critical and yet one of the most complicated and frustrating relationships that we have . '' Panetta said it is `` complicated by the fact that they maintain relationships with certain terrorist groups , that they continue to not take aggressive action with regard to these safe havens , and that they 're concerned about the sovereignty results and criticisms of the United States when , in fact , my view is that the terrorists in their country are probably the greatest threat to their sovereignty . '' For his part , Mullen , also testifying before Congress this week , said he would n't `` push back '' on the challenge of working with Pakistan . `` Some of the criticism is more than warranted . Nobody 's worked that harder than me , very frankly , with the leadership . And it 's a conscious decision , I think , that we have to make . And if we walk away from it , it 's my view it will be a much more dangerous place a decade from now , and we 'll be back . ''
Gen. Ashfaq Parvez Kayani faces `` vocal and strident criticism '' in Pakistan . Adm. Mullen is one of Kayani 's closest professional and personal allies . The Pentagon is watching to see what Kayani 's top corps commanders will do .