How does the US reconcile its policy of not supplying weapons to countries with nuclear capabilities with its decision to supply arms to Pakistan?
The ban on arms stays in place. The arms sale that was made prior to the ban, but was not delivered, is what the amendment deals with. Roughly three-fourths of the sale will be cancelled and the least controversial one-fourth delivered.
Is there a contradiction in the US non-proliferation goals and the waiver of the Pressler Amendment?
None. This only deals with sales signed and sealed prior to 1990.
Does restoration of defence supplies imply tacit approval of Pakistans nuclear programme?
This does not restore defence supplies. The ban stays in place.
Since New Delhi can be expected to reconsider its missile and nuclear options following the US decision to resume arms supplies to Islamabad, how will it affect US efforts at arms control in tense regions?
The US will do all it can to discourage an arms race.
How can the US pressure India on the NPT if it is supplying arms to Pakistan?
The premise of the question is not accurate.
Is supply of arms to Islamabad aimed at balancing Indias military and political influence in the region, or countering Russian and Iranian influence in Central Asia?
Neither. It involves keeping our word. We have signed contracts with Pakistan and should either deliver or give them their money back.