A bit of guess work. PA protects Mecca and Medina shareef, where as Americans protect the rest of KSA.
Does it ? There were no Pakistani troops visible when I went for Umra
PA protects holy cities as PA is Muslim Army therefore can be deployed freely at holy sites and can thwart Isarelis if Israelis attempt to blackmail/pressurize KSA militarily
The recent Afghan-Pakistan conflict has proved one thing Saudi Arabia will say or do nothing to help Pakistan in it's conflict with India, Iran, or Afghanistan. A remote possibility but if Saudi Arabia ever does suffer an Israeli or Iranian missile strike like Qatar, Pakistan will only make a "diplomatic " statement of protest and do nothing.
A hypothetical "war gamed " scenario on a potential attack on the Two Holy Mosques.
IF they choose to, the Israelis (and also Indians) will hit Mecca and Medina with ballistic missile or drone strikes. Saudi Arabia's feeble defense is a lone 90's era PAC 3 Patriot battery located in Mecca, which can easily be destroyed by a mass drone strike, or a hypersonic anti-radiation missile.
What exactly the Pakistani Army will do to protect the "Two Holy Places" is unclear. Pakistan itself is deficient in defense against ballistic or supersonic cruise missiles given the fact that important Pakistani air bases were hit by India using massed Brahmos attacks. Pakistan's answer to India was retaliation and escalation, which ultimately resulted in US intervention and a ceasefire.
There is no way Saudi Arabia can retaliate against a potential Israeli attack on Mecca or Medina . Saudi Arabia like Qatar will make a lot of noise and do nothing. Likewise,
IF Israel damages Mecca and Medina with missile strikes, it is highly unlikely that Pakistan will start a missile exchange with Israel on behalf of Saudi Arabia. Pakistan will however "diplomatically " protest by a foreign ministry statement condemning the strike.
The only plausible scenario for a direct Pakista-Israel clash, is an attempted retaliation by Pakistan, in case it's nuclear assets are destroyed in a joint Indian-Israeli airstrike. Both India and Israel have war-gamed this scenario, and with the Shaheen missiles operating at extreme range, all will be shot down by Israeli missile defenses. However, even if it is for optics, Pakistan is almost certain to respond. Saudi Arabia will be silent on an Indian/Israeli strike on Pakista, just as it as remained silent on the Afghanistan backed terror strikes and Afghan army aggression on Pakistan's sovereign territory.
Conclusion : The Saudi-Pakistan "defense pact" means very little
