Pakistan army keeps Khyber Pass crossing shut

Pakistan kept the Torkham border crossing into Afghanistan closed to US and Nato supply convoys for a fourth day on Sunday.

Islamabad is still angry over a coalition incursion that killed three Pakistani troops last week.

And two US missile strikes on Saturday that killed 16 people in north-west Pakistan haven't helped things, showing that the US has no intention of abandoning the strategy.

A recent surge in CIA drone-fired missile strikes in Pakistan along with Nato operations along the frontier suggests that Western forces are testing how far they can push Pakistan.

Tensions came to a head after Nato helicopters crossed the border multiple times last weekend, killing dozens of militants with air strikes.

Pakistan protested to Nato and threatened to stop aiding the coalition's convoys into Afghanistan.

It made good on its threat to cut the supply line on Thursday after two Nato helicopters killed three Pakistani soldiers.

US missile strikes on Saturday hit two houses in Datta Khel village in North Waziristan, killing 16 people.